This study investigated how printing conditions influence the fracture behaviour of 3D-printed acrylonitrile butadiene styrene (ABS) under tensile loading. Dog-bone-shaped ABS specimens were produced ...using the fusion filament fabrication technique, with varying printing angles. Tensile tests were conducted on pre-notched specimens with consistent pre-notch lengths but different orientations. Optical and scanning electron microscopies were employed to analyse crack propagation in the pre-notched specimens. In order to support experimental evidence, finite element computation was implemented to study the damage induced by the microstructural rearrangement of the filaments when subject to tensile loading. The findings revealed the simple linear correlation between the failure properties including elongation at break and maximum stress in relation to the printing angle for different pre-notch lengths. A more progressive damage was found to support the ultimate performance of the studied material. This experiment evidence was used to build a damage model of 3D-printed ABS that accounts for the onset, growth, and damage saturation. This damage modelling is able to capture the failure properties as a function of the printing angle using a sigmoid-like damage function and a modulation of the stiffness within the raster. The numerical results demonstrated that damage pattern develops as a result of the filament arrangement and weak adhesion between adjacent filaments and explains the diffuse damage kinetics observed experimentally. This study concludes with a topological law relating the notch size and orientation to the rupture properties of 3D-printed ABS. This study supports the idea of tailoring the microstructural arrangement to control and mitigate the mechanical instabilities that lead to the failure of 3D-printed polymers.
Additive manufacturing has attracted keen interest in the medical field in recent decades, especially for bone regeneration. Many additive manufacturing processes have been used to print medical ...devices such as implants, prostheses, and surgical guides, and for surgical planning in different medical fields, especially orthopedic, maxillofacial and dental surgery. Many materials can be manufactured by 3D printing with metal, ceramic, polymer or composite materials. Composite materials with organic and mineral components have been investigated to mimic bone functional and structural characteristics. In addition to the chemical composition, the modeling and optimization of the design can be optimized to enhance the biological and mechanical performance of the printed scaffolds. This review presents a comparative evaluation of different material/additive manufacturing processes, and describes the best compromises for targeted clinical applications. The advantages and drawbacks of each additive manufacturing process are described in light of the biological results and essential properties expected by patients and clinicians. Statement of significance: 3D (bio)printing appears to be an outstanding manufacturing route to revolutionize patient care with personalized medicine. Moreover, there are growing trends in the use of 3D printing in the medical education field and for surgical planning to alleviate surgeon practice and optimize esthetic results. Many reviews have described the growth of the different additive manufacturing techniques developed over time, their advantages and drawbacks and the work required to develop an accurate printable biomaterial fitting the 3D additive manufacturing process and the expectations of the final users and beneficiaries. In this review, an emphasis is placed on the expectations of patients and clinicians regarding specific final clinical applications in craniomaxillofacial, orthopedic or dental fields for a specific biomaterial/additive material
The microstructure and mechanical performance of wood-based filament is investigated in the case of Fused Deposition Modelling (FDM) technique using experimental and numerical approaches. The ...printing process of wood-PLA/PHA is conducted by varying the printing temperature, typically from 210 °C to 250 °C. The filament temperature during the laying down is measured using infra-red camera to study the thermal cycling. In addition, X-ray micro-tomography is used to evaluate the material arrangement of printed wood-PLA/PHA at different length scales. Tensile experiments are performed to rank the loss in mechanical performance with respect to the filament properties. Finally, finite element computation is considered to predict the tensile behaviour based on the implementation of the real 3D microstructure issued from X-ray micro-tomography. The results show that the wood-based filament is printable over a wide range of temperatures and exhibits a marked heat accumulation tendency at high printing temperatures. However, the limited gain in tensile performance at these temperatures makes 220 °C an optimal choice for printing wood-based filament. The elongation at break of 3D-printed wood-PLA/PHA is remarkably similar to the results observed for the filament. Finite element computation reveals that despite this apparent similarity, the associated deformation mechanisms are different.
Polyethylene terephthalate glycol (PETG) is a thermoplastic formed by polyethylene terephthalate (PET) and ethylene glycol and known for his high impact resistance and ductility. The printability of ...PETG for fused deposition modelling (FDM) is studied by monitoring the filament temperature using an infra-red camera. The microstructural arrangement of 3D printed PETG is analysed by means of X-ray micro-tomography and tensile performance is investigated in a wide range of printing temperatures from 210 °C to 255 °C. A finite element model is implemented based on 3D microstructure of the printed material to reveal the deformation mechanisms and the role of the microstructural defects on the mechanical performance. The results show that PETG can be printed within a limited range of printing temperatures. The results suggest a significant loss of the mechanical performance due to the FDM processing and particularly a substantial reduction of the elongation at break is observed. The loss of this property is explained by the inhomogeneous deformation of the PETG filament. X-ray micro-tomography results reveal a limited amount of process-induced porosity, which only extends through the sample thickness. The FE predictions point out the combination of local shearing and inhomogeneous stretching that are correlated to the filament arrangement within the plane of construction.
Tuning the infill pattern is one of the key features in additive manufacturing to optimise part weight. In this work, the effect of the infill strategy, including rate and pattern type, is studied on ...the mechanical performance of polylactic acid (PLA)-carbon composite. In particular, three types of patterns and four filling levels are combined. These combinations are evaluated by tensile loading applied on dogbone specimens. In addition, the underlined deformation mechanisms are further explored using filament-based finite element model. The numerical simulation is built from sliced models and converted into 3D meshes to predict tensile performance. The results show that the infill rate has a nonlinear effect on the density of PLA–carbon composites, and its magnitude depends on the complexity of the generated pattern. In addition, tensile loading is found to activate varied modes of shearing and uniaxial deformations depending on the pattern type. This leads to different profiles and rankings of the tensile performance and allows the infill strategy to significantly affect the part performance, along with its density.
In this study, digital light processing (DLP) was utilized to generate 3D-printed blends composed of photosensitive acrylate-modified polylactic acid (PLA) resin mixed with varying weight ratios of ...lignin extracted from softwood, typically ranging from 5 wt% to 30 wt%. The microstructure of these 3D-printed blends was examined through X-ray microtomography. Additionally, the tensile mechanical properties of all blends were assessed in relation to the weight ratio and post-curing treatment. The results suggest that post-curing significantly influences the tensile properties of the 3D-printed composites, especially in modulating the brittleness of the prints. Furthermore, an optimal weight ratio was identified to be around 5 wt%, beyond which UV light photopolymerization experiences compromises. These findings regarding acrylate-modified PLA/lignin blends offer a cost-effective alternative for producing 3D-printed bio-sourced components, maintaining technical performance in reasonable-cost, low-temperature 3D printing, and with a low environmental footprint.
This work emphasizes an innovative approach utilizing 3D imaging technology based on synchrotron radiation to assess the microstructure of second-phase iron particles and the porous structure within ...3D-printed PLA/magnetic iron composites at different printing angles. The study examines how these observations relate to the material’s ductility when processed using fused filament fabrication. In particular, this study examines the impact of one processing parameter, specifically the printing angle, on the microstructure and mechanical behaviour of a polylactic acid (PLA)–iron (PLI) composite designed for magnetic actuation. Fused filament fabrication is employed to produce PLI tensile specimens, with varied printing angles to create different layups. X-ray microtomography is utilized to analyse the microstructure, while tensile mechanical properties are evaluated for all composites, with findings discussed in relation to printing angle conditions. Scanning Electron Microscopy is used to examine the fractography of broken specimens. Results indicate that the printing angle significantly influences the tensile properties and mechanical anisotropy of 3D-printed PLI composites, with an optimal 45°/45° layup enhancing tensile performance. These findings suggest that 3D-printed PLI composites offer a cost-efficient means of producing bio-sourced, light-adaptive materials with intricate magnetic actuation capabilities. By quantifying the modulation of mechanical properties based on printing parameters that influence microstructural arrangement, the research sheds light on a novel aspect of composite material characterization.
In this study, we propose to revisit the mechanical anisotropy inferred to printed ABS polymers using fused deposition modelling by combining digital image correlation (DIC), mechanical testing and ...finite element computation. Tensile specimens are printed using different design orientations and raster angles. Monitoring of deformed samples is performed, and strain fields are derived for each configuration. Finite element modelling of the 3D-printed material behaviour is considered to shed more light on deformation mechanisms. Experimental results show that a heterogeneous strain field develops, leading to more significant strain localisation for samples printed with the main dimension aligned with the building direction. The optimal printing angle allowing the filament to be crossed at -45°/+45° shows the best behaviour with even larger elongation at break compared to the raw material. However, digital image correlation based on optical imaging shows that a limiting scale exists for revealing the effect of filament orientation on strain localisation. Finite element results reveal the nature of the strain localisation as related presence of porosity close to the frame and the development of asymmetrical filling within the printed structure.
Additive manufacturing is a modern manufacturing technology allowing the material structuring at a fine scale. This structuring affects the performance of printed parts. In this study, the ...quantification of the material arrangement in 3D printed ceramic on the mechanical performance is tackled. The experimental layout considers two main printing parameters, namely, part orientation and printing angle, where 12 different printing configurations are studied. These configurations differ in terms of filament arrangement in the building direction, and within the plane of construction. Material characterisation is undertaken through tensile testing, which are performed for vertical, lateral and longitudinal orientations, and combined with a printing angle of 0°, 15°, 30°, and 45°. In addition, Scanning Electron Microscopy is considered to study how the material symmetry affects the fractured patterns. This analysis is completed with optical imaging and is used to monitor the deformation sequences up to the rupture point. The experimental results show a wide variety of deformation mechanisms that are triggered by the studied printing configurations. This study concludes on the interpretation of the observed trends in terms of mechanical load transfer, which is related to the lack of material connectivity, and the relative orientation of the filaments with respect to the loading directions. This study also concludes on the possibility to tune the tensile performance of 3D printed ceramic material by adjusting both the part orientation and the printing angle.
This study combines experimental testing and computation analysis to reveal the role of defects and sub-micrometric microstructure in tensile behavior of hemp bast fibers. In particular, these ...structural defects represent the footprint of the processes to which the fibers elements are subject along the whole transformation chain from the plant to the end use product. Tensile experiments performed on elementary fibers and bundles in a wide diameter range (40-200 μm) are simultaneously conducted with X-ray micro-tomography observation. 3D images of ultra-fine resolution (voxel size of 280 nm) are achieved at different deformation magnitudes up to the complete failure thanks to the use of synchrotron radiation (ESRF, Grenoble, France). A Finite element (FE) model is implemented based on the conversion of the tomograms into 3D meshes. High performance computing is used to simulate the tensile response of the hemp bast fibers. In particular, the effects of notching and sub-micrometric structure of the fibers are explored. Results show the presence of different types of diffuse damage kinetics, which are related to the variability in the fiber size, surface defects and the presence of the lumen space. The damage behavior is found to be sensitive to the type of stress criterion implemented in the FE computation. The predictive analysis demonstrates the relevance of using embedded microstructure simulations to reveal the extent of stress localization and predict the failure properties in bast fibers for innovative composite manufacturing for instance.
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